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IMO slewing rings – making everything run smoothly

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Construction machinery, wind turbines, amusement park rides, tidal power plants, cranes, trams and underground trains, bottling plants for the beverage industry and precision medical devices – many of these share one thing in common: They are fitted with slewing rings made by IMO, one of the world‘s leading manufacturers of large rolling-contact bearings and installation-ready self-contained slew drives.

IMO GmbH & Co. KG, a specialist developer and manufacturer of slewing rings, recommends that operators check the lubricating greases used in their machinery on a regular basis using OELCHECK grease analyses. These analyses, which offer their customers genuine added value, have been greatly valued by IMO for a number of years.

Customers on all five continents know that IMO slewing rings can be relied on everywhere and at all times. Among other things, this makes IMO one of the world‘s leading suppliers of tower-head, blade flange, and main bearings for wind turbines, as well as blade bearings for tidal power stations. IMO‘s ball and roller slewing rings with diameters up to 6,000 mm are available for all manner of industrial applications.
Creative and extraordinary
As components often have to withstand extreme conditions, IMO‘s design engineers are constantly confronted with new challenges. The result: extraordinary ideas and creative solutions.
Even under water, IMO slewing rings work reliably to harness energy. A novel rotor blade adjustment bearing supports and adjusts the rotors of a unique tidal power plant positioned 15 m below the water. As it does so, the three-row roller bearing withstands extraordinary loads – this is despite the fact that the pressure in action on an underwater turbine is three times stronger than the pressure on a wind turbine. IMO supplies efficient solutions to problems of all kinds, and these specially designed solutions even provide some operators with unique selling points which help keep them ahead of the competition.

Lubricating greases in accordance with recommendations

IMO slewing rings are in use worldwide, and their operators are active in a wide range of sectors. Although this means that IMO doesn‘t prescribe any specific lubricating greases for ring maintenance, the experts know which lubricants deliver the right performance and which are available in each country. They pass their experience on to the operators and recommend the products that are best suited to them. Lithium and lithium complex greases with a synthetic or mineral base oil and an NLGI class of 1 to 2 are often used. Very large slewing rings need to be re-lubricated with between 50 and 100 kilograms of lubricating grease every year. In many cases, the grease is supplied by a central lubricating system.

Lubricating grease analyses with added value

IMO recommends that slewing ring operators have an OELCHECK lubricating grease analysis performed every six months. The company has held these analyses in high esteem for many years due to the added value that they offer.
OELCHECK lubricating grease analyses:

  • provide reliable information on the condition of the grease and other components
  • accompany all new IMO developments at the field test stage
  • can detect impending damage at an early stage
  • provide warnings of lubricant ageing
  • identify contaminants and their origins
  • detect mixing with other greases
  • assist with the optimisation of lubricant amounts and re-lubrication intervals
  • contribute to operational reliability and have a positive influence on maintenance costs.


„Condition monitoring has many tools for keeping track of systems. However, they don‘t sound the alarm until things become problematic. A typical example are frequency meters in wind turbines. Although they deliver a direct alert in the event that deviating frequencies are registered, by this point the damage is often already done. A lubricating grease analysis allows us to see deep into the fuel and the components, which, in most cases, enables us to intervene before any damage can develop in the first place. And we‘re right where our customers need us – our service teams are at home anywhere in the world.“


As IMO GmbH & Co. KG‘s Head of Service, Hanjo Hermann knows all about the many possibilities offered by OELCHECK lubricating grease analyses.
The analyses are also the method of choice for determining lubricant amounts and relubrication intervals for the application at hand. IMO slewing rings are put to work in a wide range of installations. To begin with, lubricant amounts and re-lubrication intervals are defined based on empirical values and the load involved. A certain safety factor is always included in calculations from the outset. OELCHECK analyses are then conducted on the slewing ring and grease during operation. Based on these results, the lubricant amounts and re-lubrication intervals are adjusted step by step until the ideal state is achieved, while keeping in mind the golden rule: „Too much re-lubrication is expensive, but too little will cost even more!“
OELCHECK‘s all-inclusive analysis kit 5 is the perfect choice for examining IMO slewing ring greases, as it enables OELCHECK‘s tribologists to derive a precise description of the condition of the grease and the lubricated component. An assessment in the lab determines the following parameters: the components are subdivided according to wear, contaminants & additives, PQ index, IR spectroscopy, water content using the Karl Fischer titration method, and penetration value.
An all-inclusive OELCHECK analysis kit and sampling kit make it simple to take samples. In the case of IMO slewing rings that are over 1,000 mm in diameter, grease samples are taken by spatula from grease outlet boreholes at two to three points as close to possible to the bearing track in the main load-bearing area. Each sample is placed in a separate sample bottle, To allow the OELCHECK lab to make valid statements as to the condition of the grease and the slewing ring.

IMO – innovation belongs to the future

The IMO Group‘s impressive success story started in 1988. For years now, the group has been among the world‘s leading producers of large rolling-contact bearings and installation-ready self-contained slew drives. As IMO products often have to withstand extreme conditions, new approaches and extraordinary ideas are continually leading to innovative solutions that are then put into practice.
Both of IMO Group‘s manufacturing sites are located in Gremsdorf in Southern Germany. Around 500 employees work at the sites in Gremsdorf as well as in the USA and China, and as part of the Group‘s global sales network.

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